1. Field of the Invention
The present invention generally relates to cylindrical grinding apparatuses and processes and, more particularly, to a holder for holding workpieces during a cylindrically grinding process and a holding method for such a process.
2. Discussion of the Related Art
Usually, optical elements such as camera lenses and spectacles are in used in cylindrical form. However, original optical workpieces (i.e. lens blanks) are most easily manufactured in the form of a square. Therefore, these original optical workpieces have to be cylindrically ground before use.
A typical example of a contemporary cylindrical grinding apparatus is a centering apparatus. The centering apparatus typically includes a pair of holders for holding the original workpiece, where each holder has a hollow chamber communicating with a surface of the holder. The holder can hold the workpiece on its surface by using an air pump pumping the hollow chamber, a grinding wheel is then used to cylindrically grind the workpiece. However, the centering apparatus can only cylindrically grind one piece of workpiece at a time.
FIGS. 6–7 show an apparatus for cylindrically grinding more than one workpiece at a time. The apparatus includes a first holding tool 30 and a second holding tool 40. The first holding tool 30 defines a holding groove 32, and the second holding tool 40 defines a semicircular groove 42. The holding groove 32 and the semicircular groove 42 are both for securing the workpieces 50 in the holding tools 30, 40. In use, firstly, a plurality of workpieces 50 are placed in the holding groove 32 of the first holding tool 30. Secondly, the workpieces 50 are bonded together using adhesive. Thirdly, a grinding wheel is used to grind a portion of the workpieces 50 projecting out of the holding groove 32 into a semicircular shape. Fourthly, the semicircular portion 51 of the workpieces 50 is transferred to the semicircular groove 42 of the second holding tool 40. Fifthly, the other portion of the workpieces 50 is also ground into a semicircular shape using the grinding wheel. The final result being that the workpieces 50 are ground to a cylindrical shape.
When transferring the workpieces 50 from the first holding tool 30 to the second holding tool 40, the adhesive should be dissolved so that the workpieces 50 can be taken out of the first holding tool 30. However, the workpieces 50 will not be compact in the second holding tool 40 because the workpieces 50 will be disarrayed whilst the adhesive is dissolved.
Therefore, an apparatus and a process for cylindrically grinding workpieces which can easily and compactly transfer the workpieces is desired.